The present invention generally relates to a system for coating substrates. More specifically, the invention relates to a plasma arc coating system.
Existing multi-plasma arc coaters incorporate resistive heaters to pre-heat a substrate before it enters into a coating chamber or station. These heaters extend over a large distance in the direction of substrate motion. Further, these heaters have poor spatial resolution in the direction transverse to substrate motion, and have a slow thermal response time relative to the substrate residence time at the heater station.
Many coating stations continuously supply reagent during the coating process, such as coating stations that employ ring manifolds for individual plasma arcs or racetrack manifolds for arc arrays. These manifolds, however, do not allow the upstream and downstream injection orifices to be fed and switched on and off independently of one another.
Moreover, in certain coating stations, arcs and manifolds are placed on opposite sides of the coating station to coat both sides of the substrate, which requires balancing opposing jets to minimize or prevent overspray. However, in a two-sided coating station, balancing opposing jets is difficult to achieve and generally can not consistently be maintained during production runs. Therefore, the opposing jets mix when the jets are not fully intercepted by a substrate, resulting in condensing precursors originating from arcs on opposite sides of the substrates.